Current-supply circuit for vacuum bulbs



S. P. SHACKLETON. CURRENT SUPPLY cmcun FOR VACUUM BULBS.

APPLICATION FILED MAY31, I919.

Patented Jan. 31,1922.

UNITED STATES PATENT OFFICE.

MIUEL P. SHAGKLETON, OF NEW YORK, N. Y., A SSIGNOR TO AMERICAN TELEPHONE dc TELEGRAPH QOMPANY, A CORPORATION OF NEW YORK.

CURRENT-SUPPLY CIRCUIT FOR VACUUM BULBS.

Specification of Letters Patent.

Patented Jan. 31, 1922.

Application filed May 81, 1919. Serial No. 300,986.

To all whom it may concern:

Be it known that I. SAMUEL P. SHACKLE- TON, residing at New York, in the county of Bronx, and State of New York, have vented certain Improvements in Current- Supply Circuits for Vacuum Bulbs, of which the following is a specification.

"This invention relates to telephone circuits, and more particularly to battery supplycircuits for repeater installations involving a plurality of vacuum bulb repeater elements.

In vacuum bulb repeater installations, in order to avoid'the provision of alarge number of se arate current supply sources for heating the filaments of the bulbs, it has V heretofore been customary to connect the filaments of two bulbs in series with a common source and also as many additional such series combinations as may be desired in parallel. It has been found that such an arrangement of vacumu bulbs in telephone repeater circuits and in telephone signaling circuits does not make economical use of the energy for heating the filaments when the present standard 24 volt central. office battery is used as the source of power for this ur-pose. This is due to the power or energy oss occurring in the external resistances in series with the filament circuits which are required to re ulate the potential supplied from the 24 b0 t battery to the desired value at the bulbs. A specific illustration of conditions. .wherein such a, .ower. or energy loss wouldbe of considerabemagnitude, would be in the case of cable .type repeater installations where the filament heating current for a large number of bulbs is supplied from a common source.

Accordingly it is a generaliobject of invention to provide vacuum bulb repeater installations wherein :the power or energy.

loss in the filament circuits will be considerreduced and whereby the arrangements operate in a much 3 more economical manner than heretofore .an d f. reduce the cost of. operation. These objects are accom plished in the arrangements of this invention by employing a secondary bus-bar sys tem forsupplying current to the bulbs. The

standard central office batteryfis connected to a ,mainjbus-bar throughlacurrent regulating mechanism so theta potential of apro'ximatel 21volts isvapplied to the mainu's-ba'r,- on'nected'in series with themai'n bus-bar are three secondary bus-bars from which current is supplied to the bulbs. \Vhen three secondary bus-bars are employed the potential drop between the secondary busbarswill be approximately 7 volts, which has been found satisfactory for the operation of the bulbs. lVith such an arrangement the filament circuits of three bulbs, instead of only two as in former arrangements, may be connected together in series, under which condition a saving in the power costs of approximately 33 per cent. is effected. It is pointed out that in order to maintain the potential drop between the secondary bus-bars the same and at approximately 7 volts, the repeater circuits must be wired so-that the same number of bulbs are connected to each bus-bar for normal operation. If some of the bulbs are cut out of operation or removed from one of the secondary bus-bars and an equivalent number is not removed from the other bus-bars, a condition of unbalance will result and there will be an unequal distribution of voltages across the bus-bars-which may be sufficientto causecurrent variations outside the allowable limits unless compensated for. In order to compensate for such a condition of unbalance between the secondary bus-bars anumber of polarized relays are connected thereto which operate whenevera number of the bulbs are cut out vofservice or-removed therefrom. These polarized relays control rheostats whereby-resistance units will be connected across thesecondary bus-bars from whichthe bulbs have been removed and thereby maintain a desired distribution of voltages across the bus-bars.

Th'e invention may be more clearly understood from the following descriptionwhen taken in connection ,with the accom necting batteryl to bus-hart, .or in the cir-.

cuit connecting; bus-bar 3 to ,bus-bar is y a voltage regulating mechanism (not. shown)v adjusted. so that a potential of approximately 21 ,volts will be applied to the sec ondary bus-bar 7. Accordingly if an equal load were distributed across bus-bars 7 and 8, Sand 9, and 9 and 10, there would be a potential drop between bus-bars 7 and 8 from 21 volts to 14 volts, and between busbars 8 and 9 from 14 volts to 7 volts, and between bus-bars 9 and 10 from 7 volts to zero. Accordingly to maintain an equal voltage distribution across the bus-bars and avoltage of approximately 7 volts which has been found suitable for satisfactory operation of the bulbs, for normal operation an equal number of bulbs are connected across each set of bus-bars. The filaments of bulbs 11, 12 and 13 are illustrated as connected across the bus-bars. Additional bulbs may be connected thereto by means of conductors such as 14, 15 and 16. Included in a bridge across bus-bars 7 and 8 is a winding of a polarized relay 17. Included in a bridge across busbars 8 and 9 is another winding of relay 17. The two windings of relay 17 are difierenr tially arranged and accordingly when the loads across the two sets of bus-bars are equal and the distribution of voltage is the same the relay will not operate. However, when a condition of unbalance exists due to some of the bulbs being removed from one set of bus-bars, more current will flow through one of the windings of the relay than through the other and the relay will operate. The operation of relay 17 serves to control the rheostat mechanism 19 whereby bridges including resistance elements, such asR, or R may be completed across either of the sets of bus-bars from which the bulbs have been removed, thereby compensating for such removal, and restoring'the apparatusto a desired condition of balance. Included in bridges across bus-bars 8 and 9. and 9 and 10, are the differentially arranged windings of a polarizedrelay 18, which is similar to relay 17. The relay 18 in turn controls a rheostat mechanism 20 similar to mechanism 19 which in a similar manner serves to compensate for unbalance in the loads connected across bus bars 8 and 9, and 9 and 10. The signal lamps 21, 22, 23, 24 and the buzzer mechanism 25 are associated with the rheostats 19 and 20 and operate whenever the unbalance becomes great enough to require manual adjustment.

The operation of the invention is as follows: If a potential of approximately 21 volts is applied from battery 1 to the secondary bus-bar 7, current will flow from bus bar 7 through the filament of vacuum bulb 11 to bus-bar 8, and through the filament of vacuum bulb 12 to bus-bar 9, and through the filament of vacuum bulb 13 to bus-bar 10 and ground. Current will also flow through other parallel circuitsincluding vacuum bulbs, as for example, vacuum bulbs connected to conductors 14, 15 and 16. If

an equal number of bulbs is connected between bus-bars 7 and 8, between bus-bars .10 from 8 and 9, and between bus-bars 9 and 10, there will be a potential drop from busbar 7 to bus-bar 8 from 21 volts to 14 volts, and from bus-bar 8 to bus-bar 9 from 14 volts to 7 volts, and from bus-bar 9 to bus-bar 7 volts to zero. Accordingly there will be an equal voltage distribution of 7 volts across each of the bus-bar branches. .\t the same time current will flow from -bus-bar '7 over conductor 26, upper winding of relay 17, conductors 27 and 28 to bus-bar 8. Current will also flow from busbar 8 over conductors 28 and 27. lower winding of relay 17, conductors 29 and 30, to bus-bar 9. It there is an equal load across bus-bars 7 and 8 and across bus-bars8 and 9 of approximately 7 volts. as pointed out, the currents flowing through the windings of relay 7 will be of equal value, and as the windings of relay 7 are differentially arranged, the relay will not be operated. However, if. for purposes of illustration. some of the bulbs are cut out of service or no longer connected across bus-bars 7 and v 8, the resistance across said bus-bars will be increased and a lesser drop in potential will take place across bus-bars 7 and 8 than across bus-bars 8 and 9. Accordingly more current will now flow through the lower winding of relay 17 than through the upper.

mechanism whereby the needle of rheostat 19 will be deflected to the right. This will complete the following bridge across busbars 7 and 8; from bus-bar 7, conductor resistance elements R needle of rheostat 19, conductor to bus-bar 8. The polar relay 17 and the relay 32 will continue to function until the proper number of resistance units in the resistance R, are included in this bridge to compensate for the removal across bus-bars 7 and 8 of the resistance of the vacuum bulbs disconnected therefrom. Theadditional resistance units thus connected in parallel across bus-bars 7 and 8 will restore a condition of balance between bus-bars 7 and 8 and bus-bars 8 and 9, so that there will be an equal potential drop across said bus-bars. Bythis means the current flowing over the filament circuits ofthe vacuum bulbs connected .across bus-bars 7 and8 will not be allowed to increase beyond desirable limits for the effeccircuit the relay 36, which is connected in parallel therewith will operate and close the following circuit: from ground, armature and contact of relay 36, conductor 37, filament of signal lamp 22, conductor 38, winding of relay 39 to battery and ground. The closing of this circuit will operate signal lam 22 and will start the buzzer apparatus 25 111130 operation, so that the repeater attendant may be notified that the automatic adjustment effected by rheostat 19 will not be sufiicient, and may adjust the mechanism manually. If a number of the bulbs normally connected across bus-bars 8 and'9 were cut out of service, the drop in potential across bus-bars 8 and 9 would be less than the drop in potential across bus-bars 7 and 8., Accordingly, when such is the case, more current will flow through the upper winding of relay 17 than through the lower winding of rela 17, and the relay 17 will be operated an its armature deflected to the right. This will close the following circuit: from ground, armature and right hand contact of relay 17, conductor 40, armature and contact of relay 41, conductor 42, winding of relay 41 to battery and ground. This .will operate the relay 41, which in turn will operate ratchet mechanism to deflect the needle of rheostat 19 to the left, and thereby include in a bridge across bus-bars 8 and 9, units of the resistance element R This bridge is completed as follows: from bus-bar 8 over conductor 35, needle of rheostat 19, resistance units R conductor 43 to bus-bar 9. The polar relay 17 and relay 41 will continue to operate until a sufiicient number of the units of resistance R are included in this bridge to cause the potential drop across bus-bars 8 and 9 to be equal to the potential drop across bus-bars 7 and 8 and thereby compensate for the removal across bus-bars 8 and 9 of the parallel resistance circuits of the vacuum bulbs cut out of service. Connected in parallel with this bridge is the relay 44 which is similar in operation to relay 36 and which will operate and close the following circuit: from ground, arma ture and contact of relay 44, conductor 45, filament of signal lamp 21, conductor 38, windingof relay 39,"to battery and ground. The closing of this circuit will operate the lamp 21 and start the buzzer apparatus 25 into operation, so that if a condition of balance between the two bus-bar branches may not be automatically effected by rheostat 19, the repeater attendant may be notified and may adjust the. apparatus manually. Bridged across bus-bars 8 and 9 is the upper winding of the polar relay 18. Bridged across bus-bars 9 and 10 is the lower winding of polar relay 18. These windings are differentially arranged. Relay 18 is similar in operation to relay 17 and controls the rheostat mechanism 20 which in turn is similar to rheostat 19. Accordingly, when the drop in potential between bus-bars 8 and 9 differs from the drop in potential from bus-bar 9 to bus-bar lO, due to the cutting out of service of some of the bulbs associated with one of these bus-bar branches, the relay 18 and the rheostat mechanism 20'will operate in a manner similar to that already pointed out to bridge across the busbars from which the bulbs have been re moved resistance units to compensate for such-removal, and to restore the branches to a condition of balance.

It is pointed out that, while the invention has been specifically illustrated in arrangements wherein three secondary bus-bars across which there is a voltage distribution of approximately 7 volts are employed, that the invention is not limited to the specific arrangements disclosed. Types of work circuits other than those including filaments of vacuum bulbs might be connected across the secondary bus-bars. In such arrange: ments a voltage distribution across the busbars of other than 7 volts or even an unequal distribution of voltage might be desirable and it might be desirable to apply to the bus-bar 7 in the first instance a potential other than approximately 21 volts. Furthermore the number of secondary busbars is not limited to three as the balancing arrangements might equally well be employed with two pairs of such bus-bars. Accordingly while the invention has been .disclosed in certain specific arrangements which have been deemed desirable, it is understood that it is capable of embodiment in many and widely varied forms as defined in the appended claims.

What is claimed is:

1. In a current supply system for work circuits, a source of current, more than three bus-bars connected in series therewith through said work circuits, and automatically operating means associated with said bus-bars for maintaining a constant potential difi'erence between adjacent pairs of said bus-bars, said automatically operating means comprising bridges across each adjacent pair of bus-bars including variable resistances, a polarized differentially wound relay, one of the windings of said relay being included in a bridge across the first and second ofsaid bus-bars, the other winding of said relay being included in a bridge across the second and third of said bus-bars, a second polarized differentially wound relay, one of the windings of said relay being included in a bridge across the second and third of said bus-bars, the other winding being included in a bridge across the third and fourth of said bus-bars, and means controlled by said relays for varying said resistances.

2. In a current supply system for work circuits, a source of current, more than three bus-bars connected in series therewith through said work circuits, and automatically operating means associated with said bus-bars for maintaining a constant po-,

tially. wound relays, each relay having windings bridged across adjacent pairs of said bus-bars and one winding of each of two adjacent relays being bridged across the same pair of bus-bars, and means controlled by 15 said relays for varying said resistances.

-In testimony whereof, I have signed my name to this specification this 28th day of May, 1919.

SAMUEL P. SHAOKLETON. 

